Semiconductor device and method of fabricating the same, circuit board, and electronic instrument

ABSTRACT

A method of fabricating a semiconductor device, including: preparing a wiring board on which is mounted a first semiconductor chip having a plurality of first pads; electrically connecting each of the first pads to an interconnecting pattern of the first semiconductor chip by a wire; providing resin paste on the first semiconductor chip; mounting a second semiconductor chip having a plurality of second pads on the first semiconductor chip with the resin paste interposed therebetween; and forming a spacer by hardening the resin paste to fix the first and second semiconductor chips together, wherein the spacer is formed to extend under the second pads and further outward; and wherein the highest portion of the wire is disposed on the outer side of the first semiconductor chip.

Japanese Patent Application No. 2003-270972, filed on Jul. 4, 2003, ishereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and a method offabrication thereof, a circuit board, together with an electronicinstrument.

It is known to fabricate a single semiconductor device by stacking aplurality of semiconductor chips with spacers therebetween. In such acase, it is also known to use wires to connect the semiconductor chipselectrically to an interconnecting pattern. In order to fabrication athin semiconductor device with superlative mounting capabilities, it ispreferable to reduce the thicknesses of the spacer and the semiconductorchips.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda method of fabricating a semiconductor device, comprising:

-   -   preparing a wiring board having an interconnecting pattern and        on which is mounted a first semiconductor chip having a        plurality of first pads;    -   electrically connecting each of the first pads to the        interconnecting pattern by a wire;    -   providing resin paste on the first semiconductor chip;    -   mounting a second semiconductor chip having a plurality of        second pads on the first semiconductor chip with the resin paste        interposed between the first and second semiconductor chips such        that at least part of the first pads is covered by the second        semiconductor chip with a space between the first and second        semiconductor chips; and    -   forming a spacer by hardening the resin paste between the first        and second semiconductor chips to fix the first and second        semiconductor chips together,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the highest portion of the wire is disposed on the outer        side of the first semiconductor chip.

According to a second aspect of the present invention, there is provideda method of fabricating a semiconductor device, comprising:

-   -   preparing a wiring board having an interconnecting pattern and        on which is mounted a first semiconductor chip having a        plurality of first pads;    -   electrically connecting each of the first pads to the        interconnecting pattern by a wire;    -   providing resin paste on the first semiconductor chip;    -   mounting a second semiconductor chip having a plurality of        second pads on the first semiconductor chip with the resin paste        interposed between the first and second semiconductor chips such        that at least part of the first pads is covered by the second        semiconductor chip with a space between the first and second        semiconductor chips; and    -   forming a spacer by hardening the resin paste between the first        and second semiconductor chips to fix the first and second        semiconductor chips together,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the wire protrudes diagonally upward from a space above        the first semiconductor chip.

According to a third aspect of the present invention, there is provideda semiconductor device comprising:

-   -   a wiring board having an interconnecting pattern;    -   a first semiconductor chip mounted on the wiring board and        having a plurality of first pads;    -   a plurality of wires which electrically connect the        interconnecting pattern and the first pads respectively;    -   a second semiconductor chip having a plurality of second pad and        mounted on the first semiconductor chip such that at least part        of the first pads is covered by the second semiconductor chip        with a space between the first and second semiconductor chips;        and    -   a spacer which is formed between the first and second        semiconductor chips and to fix the first and second        semiconductor chips,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the highest portion of each of the wires is disposed on        the outer side of the spacer.

According to a fourth aspect of the present invention, there is provideda semiconductor device comprising:

-   -   a wiring board having an interconnecting pattern;    -   a first semiconductor chip mounted on the wiring board and        having a plurality of first pads;    -   a plurality of wires which electrically connect the        interconnecting pattern and the first pads respectively;    -   a second semiconductor chip having a plurality of second pad and        mounted on the first semiconductor chip such that at least part        of the first pads is covered by the second semiconductor chip        with a space between the first and second semiconductor chips;        and    -   a spacer which is formed between the first and second        semiconductor chips and to fix the first and second        semiconductor chips,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein each of the wire protrudes diagonally upward from the        spacer.

According to a fifth aspect of the present invention, there is provideda circuit board on which is mounted any one of the above semiconductordevices.

An electronic instrument according to a sixth aspect of the presentinvention comprises any one of the above semiconductor devices.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing a method of fabricating asemiconductor device according to one embodiment of the presentinvention.

FIG. 3 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIG. 4 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIG. 5 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIG. 6 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIG. 7 is a diagram showing a method of fabricating a semiconductordevice according to one embodiment of the present invention.

FIG. 8 is a diagram showing a circuit board on which is mounted asemiconductor device according to one embodiment of the presentinvention.

FIG. 9 is a diagram showing an electronic instrument having asemiconductor device according to one embodiment of the presentinvention.

FIG. 10 is a diagram showing an electronic instrument having asemiconductor device according to one embodiment of the presentinvention.

FIGS. 11A and 11B are diagrams showing a method of fabricating asemiconductor device according to a modification of one embodiment ofthe present invention.

FIGS. 12A and 12B are diagrams showing a method of fabricating asemiconductor device according to a modification of one embodiment ofthe present invention.

FIGS. 13A and 13B are diagrams showing a method of fabricating asemiconductor device according to a modification of one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention may provide a semiconductor device havingsuperlative mounting capabilities and reliability, a method offabrication thereof, a circuit board, and an electronic instrument.

(1) According to one embodiment of the present invention, there isprovided a method of fabricating a semiconductor device, comprising:

-   -   preparing a wiring board having an interconnecting pattern and        on which is mounted a first semiconductor chip having a        plurality of first pads;    -   electrically connecting each of the first pads to the        interconnecting pattern by a wire;    -   providing resin paste on the first semiconductor chip;    -   mounting a second semiconductor chip having a plurality of        second pads on the first semiconductor chip with the resin paste        interposed between the first and second semiconductor chips such        that at least part of the first pads is covered by the second        semiconductor chip with a space between the first and second        semiconductor chips; and    -   forming a spacer by hardening the resin paste between the first        and second semiconductor chips to fix the first and second        semiconductor chips together,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the highest portion of the wire is disposed on the outer        side of the first semiconductor chip.

In this method, the spacer is formed to extend under the second pads ofthe second semiconductor chip and further outward. This ensures that thesecond semiconductor chip is difficult to break, even if a load isapplied to the second pads. In addition, the highest portion of eachwire is disposed on the outer side of the first semiconductor chip. Inother words, the height of the wires can be reduced above the firstsemiconductor chip. This makes it difficult for the wires to move, evenwhen the resin paste flows, thus making it possible to preventshort-circuiting between neighboring wires. These features enable thefabrication of a highly reliable semiconductor device.

(2) According to one embodiment of the present invention, there isprovided a method of fabricating a semiconductor device, the methodcomprising:

-   -   preparing a wiring board having an interconnecting pattern and        on which is mounted a first semiconductor chip having a        plurality of first pads;    -   electrically connecting each of the first pads to the        interconnecting pattern by a wire;    -   providing resin paste on the first semiconductor chip;    -   mounting a second semiconductor chip having a plurality of        second pads on the first semiconductor chip with the resin paste        interposed between the first and second semiconductor chips such        that at least part of the first pads is covered by the second        semiconductor chip with a space between the first and second        semiconductor chips; and    -   forming a spacer by hardening the resin paste between the first        and second semiconductor chips to fix the first and second        semiconductor chips together,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the wire protrudes diagonally upward from a space above        the first semiconductor chip.

In this method, the spacer is formed to extend under the second pads ofthe second semiconductor chip and further outward. This ensures that thesecond semiconductor chip is difficult to break, even if a load isapplied to the second pads. Each wire is provided to protrude diagonallyupward from the space above the semiconductor chip. In other words, itis possible to reduce the height of the wire in the space above thefirst semiconductor chip. This makes it difficult for the wires to move,even when the resin paste flows, thus making it possible to preventshort-circuiting between neighboring wires. These features enable thefabrication of a highly reliable semiconductor device.

(3) This method of fabricating a semiconductor device may furthercomprise making the resin paste flow out over the wiring board from thefirst semiconductor chip to form a fillet surrounding the firstsemiconductor chip. This forms the fillet around the first semiconductorchip on the wiring board. This means that the first semiconductor chipand the wiring board are protected by the fillet, enabling thefabrication of a highly reliable semiconductor device.

(4) In this method of fabricating a semiconductor device, the resinpaste may be provided only over the first semiconductor chip; and theresin paste may flow out over the wiring board in the step of mountingthe second semiconductor chip.

(5) In this method of fabricating a semiconductor device, the resinpaste may include a plurality of insulating balls; and the insulatingballs may be interposed between the first and second semiconductorchips.

(6) In this method of fabricating a semiconductor device, the step ofelectrically connecting the first pads to the interconnecting patternmay include connecting the wire electrically to the interconnectingpattern at first and then connecting the wire electrically to one of thefirst pads.

(7) In this method of fabricating a semiconductor device, the step ofelectrically connecting the first pads to the interconnecting patternmay include connecting the wire electrically to one of the first pads atfirst and then connecting the wire electrically to the interconnectingpattern.

(8) This method of fabricating a semiconductor device may furthercomprise electrically connecting each of the second pads to theinterconnecting pattern by a wire, after the step of hardening the resinpaste.

(9) According to one embodiment of the present invention, there isprovided a semiconductor device comprising:

-   -   a wiring board having an interconnecting pattern;    -   a first semiconductor chip mounted on the wiring board and        having a plurality of first pads;    -   a plurality of wires which electrically connect the        interconnecting pattern and the first pads respectively;    -   a second semiconductor chip having a plurality of second pad and        mounted on the first semiconductor chip such that at least part        of the first pads is covered by the second semiconductor chip        with a space between the first and second semiconductor chips;        and    -   a spacer which is formed between the first and second        semiconductor chips and to fix the first and second        semiconductor chips,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein the highest portion of each of the wires is disposed on        the outer side of the spacer.

In this semiconductor device, the spacer is formed in such a manner thatit extends under the second pads of the second semiconductor chip andfurther outward. This ensures that the second semiconductor chip isdifficult to break, even if a load is applied to the second pads. Thewires are disposed in such a manner that the highest portions thereofare disposed on the outer side of the spacer. In other words, the heightof the wires can be reduced above the first semiconductor chip. Thismakes it possible to reduce the thickness of the spacer. These featuresenable the provision of a semiconductor device which is highly reliableand which has superior mounting capabilities.

(10) According to one embodiment of the present invention, there isprovided a semiconductor device comprising:

-   -   a wiring board having an interconnecting pattern;    -   a first semiconductor chip mounted on the wiring board and        having a plurality of first pads;    -   a plurality of wires which electrically connect the        interconnecting pattern and the first pads respectively;    -   a second semiconductor chip having a plurality of second pad and        mounted on the first semiconductor chip such that at least part        of the first pads is covered by the second semiconductor chip        with a space between the first and second semiconductor chips;        and    -   a spacer which is formed between the first and second        semiconductor chips and to fix the first and second        semiconductor chips,    -   wherein the spacer is formed to extend under the second pads and        further outward; and    -   wherein each of the wire protrudes diagonally upward from the        spacer.

In this semiconductor device, the spacer is formed in such a manner thatit extends under the second pads of the second semiconductor chip andfurther outward. This ensures that the second semiconductor chip isdifficult to break, even if a load is applied to the second pads. Thewires are provided in such a manner that they protrude diagonally upwardfrom the spacer. In other words, it is possible to reduce the height ofthe wires above the first semiconductor chip. This makes it possible toreduce the thickness of the spacer. These features enable the provisionof a semiconductor device which is highly reliable and which hassuperior mounting capabilities.

(11) This semiconductor device may further comprise a fillet disposedaround the first semiconductor chip on the wiring board. This enablesthe fillet to reduce the effects of external forces on the firstsemiconductor chip and the wiring board. It is therefore possible toprovide an even more reliable semiconductor device.

(12) In this semiconductor device, the spacer and the fillet may be ofthe same material.

(13) In this semiconductor device, the spacer may include a plurality ofinsulating balls.

(14) According to one embodiment of the present invention, there isprovided a circuit board on which is mounted any of the abovesemiconductor devices.

(15) According to one embodiment of the present invention, there isprovided an electronic instrument comprising any of the abovesemiconductor devices.

Embodiments of the present invention will be described below withreference to the accompanying figures. It should be noted, however, thatthe present invention is not limited to the embodiments below. A methodof fabricating a semiconductor device in accordance with one embodimentof the present invention is illustrated in FIGS. 1 to 7.

A method of fabricating a semiconductor device according to oneembodiment of the present invention includes a step of preparing of awiring board 20 on which is mounted a first semiconductor chip 10 andhaving an interconnecting pattern 22, as shown in FIG. 1.

An integrated circuit 12 formed of components such as transistors andmemory elements could be formed on the first semiconductor chip 10. Aplurality of first pads 14 is formed on the first semiconductor chip 10.The first pads 14 could be connected electrically to the interior of thefirst semiconductor chip 10. The first pads 14 could also be connectedelectrically to the integrated circuit 12. Alternatively, theconfiguration could include pads that are not connected electrically tothe integrated circuit 12, which are called the first pads 14. The firstpads 14 could be disposed at along two or four edges at end portions ofone surface, or they could be disposed at a central portion. Inaddition, bumps (not shown in the figures) could be formed on the firstpads 14. The first pads 14 could be formed of a metal such as analuminum or copper type of metal. A passivation film (not shown in thefigures) could also be formed over the first semiconductor chip 10,avoiding the central portion of each of the first pads 14. Thepassivation film could be formed of a material such as SiO₂, SiN, or apolyimide resin. Note that the shape in plan view of the firstsemiconductor chip 10 is not particularly limited, but it could be arectangle (which includes a square), by way of example.

The wiring board 20 could be formed of any of a variety of organicmaterials (such as a polyimide substrate) or inorganic materials (suchas a ceramic substrate or a glass substrate), or it could have astructure that is a composite of such materials (such as a glass-epoxysubstrate). The shape in plan view of the wiring board 20 is notparticularly limited, but it is most usually rectangular. The wiringboard 20 could be a single-layer or a multi-layer substrate. The wiringboard 20 could be a tape-shaped flexible substrate or a rigid substrate.The wiring board 20 could be termed an interposer. The wiring board 20has the interconnecting pattern 22. The material of the interconnectingpattern 22 is not particularly limited, but it could have layers formedof Cu, by way of example. The interconnecting pattern 22 could be formedas either a single layer or as a plurality of layers. A plurality ofthrough-holes 24 could be formed in the wiring board 20 to electricallyconnect one surface of the board to the other surface thereof. Thethrough-holes 24 could be filled with conductive members (see FIG. 1),or they could be formed as through-holes with inner wall surfacesfinished by plating. This enables electrical contact with both surfacesof the wiring board 20.

With this embodiment, the first semiconductor chip 10 is mounted on thewiring board 20. The first semiconductor chip 10 could be mounted on thewiring board 20 in such a manner that the surface thereof that isopposite to the surface on which the pads 14 are formed faces the wiringboard 20, as shown in FIG. 1. The first semiconductor chip 10 could befixed to the wiring board 20 by adhesive 16. In this case, an insulatingadhesive could be used as the adhesive 16.

Note that this embodiment could configure a semiconductor device inwhich one wiring board 20 is mounted on one first semiconductor chip 10.However, it should be noted that it is also possible to mount aplurality of first semiconductor chips on one wiring board, to form aplurality of semiconductor devices in one batch.

The method of fabricating a semiconductor device in accordance with thisembodiment includes a step of electrically connecting each of the firstpads 14 to the interconnecting pattern 22 by a wire 30 (see FIG. 2B).The material of the wire 30 is not particularly limited, but gold wirecould be used therefor, by way of example. With this embodiment, thewire 30 is provided in such a manner that the highest portion thereof isdisposed on the outer side of the first semiconductor chip 10, as shownin FIG. 2B. In other words, the wire 30 is provided to protrudediagonally upward from the space above the first semiconductor chip 10.This makes it possible to reduce the height of the wire within the spaceabove the first semiconductor chip 10. Since this makes it possible toreduce the thickness of a spacer 60 (which will be described later), itenables the fabrication of a semiconductor device having superiormounting capabilities. Since the height of the wire 30 is reduced in thespace above the first semiconductor chip 10, this makes it possible toprevent large movements of the wire 30 caused by the flowing of a resinpaste 40, which will be described later. For that reason, it is possibleto construct a highly reliable semiconductor device.

The wires 30 could be provided by any previously known method. Forexample, the wires 30 could be provided by first electrically connectingeach wire 30 to the interconnecting pattern 22 (see FIG. 2A) thenelectrically connecting the wire 30 to the corresponding first pad 14(see FIG. 2B). This makes it possible to reduce the angle subtended bythe wire 30 and the first semiconductor chip 10. The height of the wirecan be reduced thereby and it also makes it possible to fabricate asemiconductor device with superior mounting capabilities. Note thatbumps could be formed on the first pads 14 in such a case (although thisis not shown in the figures). In general, ultrasonic waves or heat areapplied to the wires or electrodes when the wires are connected to theelectrodes. The formation of a bump on each of the pads makes itpossible to protect the first semiconductor chip 10 (particularly theintegrated circuit 12) from such stresses, thus enabling the fabricationof an even more reliable semiconductor device.

The method of fabricating a semiconductor device in accordance with thisembodiment includes a step of providing the resin paste 40 over thefirst semiconductor chip 10, as shown in FIG. 3. The resin paste 40could be of a hardening type. The hardening of the resin paste 40 formsthe spacer 60. The material of the resin paste 40 is not particularlylimited, but a resin that exhibits an adhesive force on hardening couldbe used therefor. The resin paste 40 could also have insulatingproperties. The resin paste 40 could be provided by using a dispenser todrop the resin paste 40 (potting). The resin paste 40 could be providedon the first semiconductor chip 10 alone, in which case it could beprovided on a region within the first pads 14 (see FIG. 3). It should benoted, however, that the resin paste 40 could also be provided so as toextend over a region in which the first pads 14 have already beenformed, although this is not shown in the figures).

The method of fabricating a semiconductor device in accordance with thisembodiment includes a step of mounting a second semiconductor chip 50 onthe first semiconductor chip 10, as shown in FIG. 4. The details givenin the description of the first semiconductor chip 10 can also apply tothe second semiconductor chip 50. For example, the second semiconductorchip 50 could have an integrated circuit 52. A plurality of second pads54 could be formed on the second semiconductor chip 50. Note that theouter dimensions are not limited in any way and they could be the sameas those of the first semiconductor chip 10. In this embodiment, thesecond semiconductor chip 50 is mounted on the first semiconductor chip10 with the resin paste 40 therebetween, in such a manner that at leastpart of the first pads 14 is covered by the second semiconductor chip 50with a space between the first and second semiconductor chips (see FIG.5). In such a case, the second semiconductor chip 50 could also bemounted in such a manner that a surface of the second semiconductor chip50 opposite to the surface on which the second pads 54 are formed facesthe first semiconductor chip 10 (or the resin paste 40), as shown inFIG. 4. The second semiconductor chip 50 could also be mounted so as notto touch the wires 30. This makes it possible to preventshort-circuiting between the wires 30 and the second semiconductor chip50, enabling the fabrication of a highly reliable semiconductor device.Note that the surface of the second semiconductor chip 50 that faces thefirst semiconductor chip 10 could have an insulating layer formedthereon (although this is not shown in the figures). This also makes itpossible to prevent short-circuiting between the wires 30 and the secondsemiconductor chip 50.

A method of fabricating a semiconductor device in accordance with thisembodiment includes a step of causing the resin paste 40 to harden, toform the spacer 60 between the first semiconductor chip 10 and thesecond semiconductor chip 50 and fix the first and second semiconductorchips 10 and 50 together, as shown in FIG. 5. The processing forhardening the resin paste 40 differs with the type of resin paste 40,but a method such as thermal processing or irradiation with ultravioletrays could be considered. The method of fabricating a semiconductordevice in accordance with this embodiment ensures that the spacer 60 isformed and the first and second semiconductor chips 10 and 50 are fixedtogether by causing the resin paste 40 to harden. In other words, thestep of forming the spacer 60 and the step of fixing together the firstand second semiconductor chips 10 and 50 are done at the same time. Thisenables efficient fabrication of the semiconductor device.

In the method of fabricating a semiconductor device in accordance withthis embodiment, the spacer 60 is formed so as to extend under thesecond pads 54 and further outward (see FIG. 5). In such a case, thesurface of the spacer 60 in contact with the second semiconductor chip50 could be formed to extend under the second pads 54 and furtheroutward. This enables the spacer 60 to support the second semiconductorchip 50 over a wide area. This ensures that the second semiconductorchip 50 is not readily damaged, even if an external force is applied tothe second semiconductor chip 50, enabling the fabrication of a highlyreliable semiconductor device. In particular, this configuration makesit possible to prevent damage to the second semiconductor chip 50 due toforces applied in the vicinity of the second pads 54 during the bondingof the wires to the second pads 54 of the second semiconductor chip 50.The spacer 60 could be formed at any desired position and size, byadjusting the position and quantity of the resin paste 40 or bycontrolling the force pressing down on the second semiconductor chip 50,by way of example. Note that the spacer 60 could be formed within theregion of the second semiconductor chip 50, as shown in FIG. 5.Alternatively, the spacer 60 could be formed to extend to the outside ofthe second semiconductor chip 50 (although this is not shown in thefigures). This would enable similar effects.

A method of fabricating a semiconductor device in this embodiment mayinclude a step of electrically connecting the second pads 54 and theinterconnecting pattern 22 by other wires 35, as shown in FIG. 6. Thisstep is performed after the step of hardening the resin paste 40 to formthe spacer 60. As described previously, the spacer 60 of this embodimentis formed to extend further outward than the undersides of the secondpads 54. For that reason, the provision of the wires 35 after theformation of the spacer 60 makes it possible to prevent damage to thesecond semiconductor chip 50 in the step of providing the wires 35. Notethat the wires 35 could be provided by any previously known method. Inother words, the wires 35 could be provided by first electricallyconnecting each wire 35 to the interconnecting pattern 22 thenelectrically connecting the wire 35 to the corresponding second pad 54,in a similar step to that of providing the wire 30. This makes itpossible to reduce the height of the wires 35, enabling the fabricationof a semiconductor device with superior mounting capabilities. It shouldbe noted, however, that the wire 35 could be provided in such a mannerthat the wire 35 is first connected electrically to the correspondingsecond pad 54 and then the wire 35 is connected electrically to theinterconnecting pattern 22.

Note that it is also possible to fabrication a semiconductor devicehaving two or more semiconductor chips, by repeating the same steps. Asemiconductor device 1 shown in FIG. 7 can be fabricating by a step offorming a sealing portion that seals in components such as the first andsecond semiconductor chips 10 and 50 and the wires 30 and 35 and a stepof forming external terminals 72.

The semiconductor device in accordance with this embodiment of thepresent invention includes the wiring board 20 having theinterconnecting pattern 22. The semiconductor device 1 includes thefirst semiconductor chip 10 mounted on the wiring board 20 and havingthe plurality of first pads 14 formed thereon. The semiconductor device1 includes the wires 30 that electrically connect the interconnectingpattern 22 and each of the first pads 14. The semiconductor device 1includes the second semiconductor chip 50 having a plurality of secondpads 54 and mounted on the first semiconductor chip 10 in such a mannerthat at least part of the first pads 14 is covered by the secondsemiconductor chip 50 with a space between the first and secondsemiconductor chips. The semiconductor device 1 includes the spacer 60which is formed between the first semiconductor chip 10 and the secondsemiconductor chip 50 and which fixes together the first and secondsemiconductor chips 10 and 50. The spacer 60 is formed so as to extendunder the second pads 54 and further outward. Each wire 30 is providedin such a manner that the highest portion thereof is disposed on theouter side of the spacer 60. In other words, the wire 30 is provided insuch a manner that it protrudes diagonally upward from the spacer 60.Note that the semiconductor device 1 could further include structuraldetails that can be derived by those skilled in the art from the detailsdescribed with reference to this method of fabricating a semiconductordevice.

As described above, the semiconductor device 1 in accordance with thisembodiment of the present invention has the spacer 60 that is formed toextend under the second pads 54 and further outward. For that reason, awide portion of the second semiconductor chip 50 is supported by thespacer 60. This ensures that the second semiconductor chip 50 is notreadily damaged, even if an external force is applied to the secondsemiconductor chip 50, making it possible to provide a highly reliablesemiconductor device. In addition, the wire 30 is disposed in such amanner that the highest portion thereof is disposed on the outer side ofthe spacer 60. In other words, the wire 30 protrudes diagonally upwardfrom the spacer 60. This makes it possible to reduce the height of thewire 30 within the space above the first semiconductor chip 10. Sincethis ensures that the spacer 60 can be made thinner, it enables thefabrication of a semiconductor device with superior mountingcapabilities. Note that in this case, the wire 30 could be disposed insuch a manner that the highest portion thereof is on the outer side ofthe first semiconductor chip 10 too. In other words, the wire 30 couldbe provided in such a manner that it protrudes diagonally upward fromthe space above the first semiconductor chip 10. This makes it possibleto obtain similar effects. A circuit board 1000 on which is mounted thesemiconductor device 1 in accordance with this embodiment is shown inFIG. 8. A notebook personal computer 2000 shown in FIG. 9 and a portablephone 3000 shown in FIG. 10 are examples of electronic instrumentshaving the semiconductor device 1.

Modifications

The present invention is not limited to the above-described embodimentand thus various modifications thereto are possible. For example, themethod of fabricating a semiconductor device could further include astep of causing the resin paste 40 to flow out from the firstsemiconductor chip on to the wiring board 20 to form a fillet 65surrounding the first semiconductor chip 10 (see FIG. 11B). In the stepof providing the resin paste 40, the resin paste 40 could be providedonly on the first semiconductor chip 10 (see FIG. 3), then in the stepof mounting the second semiconductor chip 50, the second semiconductorchip 50 could be mounted in such a manner that the resin paste 40 flowsout over the wiring board 20 (see FIG. 11A). It should be noted,however, that the resin paste 40 could be provided in such a manner thatis flows out from the first semiconductor chip 10 during the step ofproviding the resin paste 40. The resin paste 40 could then be made toharden, to form the spacer 60 and the fillet 65 (see FIG. 11B). In thiscase, the fillet 65 is disposed around the first semiconductor chip 10on the wiring board 20. The fillet 65 and the spacer 60 are formed ofthe same material. In this modification, the first semiconductor chip 10is protected by the fillet 65, enabling the fabrication of an even morereliable semiconductor device. In particular, this enables thefabrication of a semiconductor device that is highly reliable withrespect to external forces. In addition, the method described hereinmakes it unnecessary to provide an extra step of forming the fillet 65,enabling efficient fabrication of the semiconductor device.

In a modification shown in FIGS. 12A and 12B, a resin paste 80 havinginsulating balls 82 included therein is used. In other words, the resinpaste 80 that includes the insulating balls 82 is provided on the firstsemiconductor chip 10 (see FIG. 12A), and then the second semiconductorchip 50 is mounted on the first semiconductor chip 10 with the balls 82interposed between the first and second semiconductor chips 10 and 50. Aspacer 85 having a plurality of the balls therein could be formed byhardening this resin paste (see FIG. 12B). This makes it possible tolimit the disposition of the second semiconductor chip 50 by the balls82, enabling simple mounting of the second semiconductor chip 50.

In another modification shown in FIGS. 13A and 13B, the wires 30 areprovided by first electrically connecting each wire 30 to thecorresponding first pad 14 (see FIG. 13A), then electrically connectingthe wire 30 and the interconnecting pattern 22 (see FIG. 13B). In thiscase too, the wire 30 can be provided in such a manner that the highestportion of the wire 30 is disposed on the outer side of the firstsemiconductor chip 10, making it possible to reduce the height of thewire 30 above the first semiconductor chip 10. Since the wire 30 isextracted diagonally upward, it is possible to provide the wire with noabrupt bends. This makes it possible to reduce damage to the wires 30,enabling the fabrication of a highly reliable semiconductor device.

The description of the above embodiments can be applied to theconfiguration and fabrication method of these modifications other thanthose described above. In addition, the configuration of a semiconductordevice according to one embodiment of the present invention could beformed of a combination of any components in the above description.

Note that the present invention is not limited to the above-describedembodiments, and various modifications can be made. For example, thepresent invention includes various other configurations substantiallythe same as the configurations described in the embodiments (such as aconfiguration having the same function, method, and result or aconfiguration having the same objective and result). The presentinvention also includes a configuration in which an unsubstantialportion in the described embodiments is replaced. The present inventionalso includes a configuration having the same effects as theconfigurations described in the embodiments, or a configuration able toachieve the same objective. Further, the present invention includes aconfiguration in which a publicly known technique is added to theconfigurations in the embodiments.

1. A method of fabricating a semiconductor device, comprising: preparinga wiring board having an interconnecting pattern and on which is mounteda first semiconductor chip having a plurality of first pads;electrically connecting each of the first pads to the interconnectingpattern by a wire; providing resin paste on the first semiconductorchip; mounting a second semiconductor chip having a plurality of secondpads on the first semiconductor chip with the resin paste interposedbetween the first and second semiconductor chips such that at least partof the first pads is covered by the second semiconductor chip with aspace between the first and second semiconductor chips; and forming aspacer by hardening the resin paste between the first and secondsemiconductor chips to fix the first and second semiconductor chipstogether, wherein the spacer is formed to extend under the second padsand further outward; and wherein the highest portion of the wire isdisposed on the outer side of the first semiconductor chip.
 2. A methodof fabricating a semiconductor device, the method comprising: preparinga wiring board having an interconnecting pattern and on which is mounteda first semiconductor chip having a plurality of first pads;electrically connecting each of the first pads to the interconnectingpattern by a wire; providing resin paste on the first semiconductorchip; mounting a second semiconductor chip having a plurality of secondpads on the first semiconductor chip with the resin paste interposedbetween the first and second semiconductor chips such that at least partof the first pads is covered by the second semiconductor chip with aspace between the first and second semiconductor chips; and forming aspacer by hardening the resin paste between the first and secondsemiconductor chips to fix the first and second semiconductor chipstogether, wherein the spacer is formed to extend under the second padsand further outward; and wherein the wire protrudes diagonally upwardfrom a space above the first semiconductor chip.
 3. The method offabricating a semiconductor device as defined in claim 1, furthercomprising: making the resin paste flow out over the wiring board fromthe first semiconductor chip to form a fillet surrounding the firstsemiconductor chip.
 4. The method of fabricating a semiconductor deviceas defined in claim 2, further comprising: making the resin paste flowout over the wiring board from the first semiconductor chip to form afillet surrounding the first semiconductor chip.
 5. The method offabricating a semiconductor device as defined in claim 3, wherein: theresin paste is provided only over the first semiconductor chip; and theresin paste flows out over the wiring board in the step of mounting thesecond semiconductor chip.
 6. The method of fabricating a semiconductordevice as defined in claim 4, wherein: the resin paste is provided onlyover the first semiconductor chip; and the resin paste flows out overthe wiring board in the step of mounting the second semiconductor chip.7. The method of fabricating a semiconductor device as defined in claim1, wherein: the resin paste includes a plurality of insulating balls;and the insulating balls are interposed between the first and secondsemiconductor chips.
 8. The method of fabricating a semiconductor deviceas defined in claim 2, wherein: the resin paste includes a plurality ofinsulating balls; and the insulating balls are interposed between thefirst and second semiconductor chips.
 9. The method of fabricating asemiconductor device as defined in claim 1, wherein the step ofelectrically connecting the first pads to the interconnecting patternincludes connecting the wire electrically to the interconnecting patternat first and then connecting the wire electrically to one of the firstpads.
 10. The method of fabricating a semiconductor device as defined inclaim 2, wherein the step of electrically connecting the first pads tothe interconnecting pattern includes connecting the wire electrically tothe interconnecting pattern at first and then connecting the wireelectrically to one of the first pads.
 11. The method of fabricating asemiconductor device as defined in claim 1, wherein the step ofelectrically connecting the first pads to the interconnecting patternincludes connecting the wire electrically to one of the first pads atfirst and then connecting the wire electrically to the interconnectingpattern.
 12. The method of fabricating a semiconductor device as definedin claim 2, wherein the step of electrically connecting the first padsto the interconnecting pattern includes connecting the wire electricallyto one of the first pads at first and then connecting the wireelectrically to the interconnecting pattern.
 13. The method offabricating a semiconductor device as defined in claim 1, furthercomprising: electrically connecting each of the second pads to theinterconnecting pattern by a wire, after the step of hardening the resinpaste.
 14. The method of fabricating a semiconductor device as definedin claim 2, further comprising: electrically connecting each of thesecond pads to the interconnecting pattern by a wire, after the step ofhardening the resin paste.
 15. A semiconductor device comprising: awiring board having an interconnecting pattern; a first semiconductorchip mounted on the wiring board and having a plurality of first pads; aplurality of wires which electrically connect the interconnectingpattern and the first pads respectively; a second semiconductor chiphaving a plurality of second pad and mounted on the first semiconductorchip such that at least part of the first pads is covered by the secondsemiconductor chip with a space between the first and secondsemiconductor chips; and a spacer which is formed between the first andsecond semiconductor chips and to fix the first and second semiconductorchips, wherein the spacer is formed to extend under the second pads andfurther outward; and wherein the highest portion of each of the wires isdisposed on the outer side of the spacer.
 16. A semiconductor devicecomprising: a wiring board having an interconnecting pattern; a firstsemiconductor chip mounted on the wiring board and having a plurality offirst pads; a plurality of wires which electrically connect theinterconnecting pattern and the first pads respectively; a secondsemiconductor chip having a plurality of second pad and mounted on thefirst semiconductor chip such that at least part of the first pads iscovered by the second semiconductor chip with a space between the firstand second semiconductor chips; and a spacer which is formed between thefirst and second semiconductor chips and to fix the first and secondsemiconductor chips, wherein the spacer is formed to extend under thesecond pads and further outward; and wherein each of the wire protrudesdiagonally upward from the spacer.
 17. The semiconductor device asdefined in claim 15, further comprising: a fillet disposed around thefirst semiconductor chip on the wiring board.
 18. The semiconductordevice as defined in claim 16, further comprising: a fillet disposedaround the first semiconductor chip on the wiring board.
 19. Thesemiconductor device as defined in claim 17, wherein the spacer and thefillet are of the same material.
 20. The semiconductor device as definedin claim 18, wherein the spacer and the fillet are of the same material.21. The semiconductor device as defined in claim 15, wherein the spacerincludes a plurality of insulating balls.
 22. The semiconductor deviceas defined in claim 16, wherein the spacer includes a plurality ofinsulating balls.
 23. A circuit board on which is mounted thesemiconductor device as defined in claim
 15. 24. A circuit board onwhich is mounted the semiconductor device as defined in claim
 16. 25. Anelectronic instrument comprising the semiconductor device as defined inclaim
 15. 26. An electronic instrument comprising the semiconductordevice as defined in claim 16.